JPH07137414A - Printing drum of rotary stencil printer - Google Patents

Abstract

PURPOSE:To bulge a printing drum of a flexible cylindrical body in a rotary stencil printer by an inner pressing roller more easily and uniformly over the full printing width. CONSTITUTION:A flexible porous sheet 20 is wound into a cylindrical body as a main part of a printing drum so that the both side edges thereof can seat on the outer peripheral. surfaces of a pair of ring parts 10a, 10b. An inner peripheral length of the flexible cylindrical body is previously determined to be larger than the outer peripheral length of the ring part by a predetermined dimension allowing a required bulge deformation of the flexible cylindrical body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary stencil printing machine, and more particularly to the structure of its printing drum.

[0002]

2. Description of the Related Art The same applicant as the applicant of the present invention can quickly start up a rotary stencil printing machine at the time of start-up and obtain a stencil printed matter of good finish from the first to second sheets with almost no need for trial printing. It is possible to operate by pushing each printing paper between the printing drum and the back-pressing roller, and separating the printing drum and the back-pressing roller from each other at the printing break between the printing papers. In the rotary type stencil printing machine, it is necessary to frequently reciprocate a member having a considerable mass such as a printing drum or a back-pressing roller, which restricts an increase in printing speed. ,
Instead of the traditional rigid cylindrical printing drum, the main part between both ends of the printing drum on which the stencil sheet is wound is composed of a flexible perforated sheet, and along the inner surface of the cylindrical body. A part of the cylindrical body is bulged outward in the radial direction by the rolling centering roller, and the printing drum is rotated when printing on the printing paper, while the centering roller opposes the backing roller. Inflate a part of the body one by one,
Japanese Patent Application No. 63-28553 (Japanese Patent Application Laid-Open No. 1-2047) discloses a rotary stencil printing device which is capable of performing stencil printing on a printing paper sandwiched between a backing roller and a bulging portion of a flexible cylinder.
No. 81), and a further improvement thereof is a flexible porous sheet in which the above-mentioned flexible cylinder has a rectangular expanded shape, and both ends of the flexible drum form the both ends of the printing drum. Japanese Patent Application No. 1-4702 of a rotary stencil printing machine having a structure in which each of the two annular portions is freely seated on the outer peripheral surface thereof.
No. 9 (Japanese Patent Laid-Open No. 2-225078).

When the flexible perforated sheet is a sheet such as a net material formed by woven, non-woven or knitted wire rods, two annular portions forming both ends of the printing drum at both side edge portions. When the intermediate portion of the flexible porous sheet wound in a cylindrical shape while being seated on the outer peripheral surface of the section is pushed outward in the radial direction by the intermediate pushing roller, the flexible porous sheet is pushed by the intermediate pushing roller. Further, it is possible to obtain a stencil printed matter that bulges outward in the radial direction almost uniformly over the entire width and has a uniform finish over the entire width direction. In this case, in particular, as in the above-mentioned improved type, a flexible porous sheet having a rectangular expanded shape is wound into a cylindrical body with both side edges freely seated on the outer peripheral surface of the annular portion. During this time, the cylinder exhibits greater flexibility and uniformity against radial outward swelling by the centering roller.

[0004]

However, the cylindrical body is more uniformly extruded over the entire area in the widthwise direction against the outward pressing in the radial direction by the intermediate pressing roller, and the printing speed is further increased. In order to achieve this, it is desired that the cylindrical body has a structure that is more lightly and uniformly bulged with respect to the outward pushing in the radial direction by the intermediate pressing roller.

In view of the above-mentioned circumstances, the present invention expands even more lightly and uniformly when the flexible porous sheet constituting the cylindrical body of the printing drum is pushed outward from the inside by the intermediate pushing roller. It is an object of the invention to provide a printing drum of a rotary stencil printing machine which is improved so as to be issued.

[0006]

According to the present invention, there is provided a printing drum including a cylindrical body having a porous structure for carrying a perforated stencil sheet in a wound state. The ink supplied from the inside is pressed by an intermediate pressing roller that rolls along the inner surface of the cylindrical body and is supplied to the stencil sheet through the holes of the cylindrical body, and a part of the cylindrical body is predetermined by the intermediate pressing roller. Of a rotary stencil printing machine for performing stencil printing on the printing paper pressed against the cylindrical body by the back-pressing means when the printing drum is rotated while being bulged outward in the radial direction by a substantial bulge amount of A printing drum, comprising two annular portions forming both end portions of the printing drum and a cross-section provided with a stencil sheet starting edge attaching device for connecting the two annular sections and selectively attaching the starting edge of the stencil sheet. Frame body including, both sides And a flexible perforated sheet forming a main part of the cylindrical body having a substantially rectangular expanded shape that can be freely seated on the outer peripheral surface of each of the two annular parts. The inner peripheral length of the cylindrical body is made larger than the peripheral length of the outer peripheral surface of the annular portion by a predetermined dimension that allows the predetermined amount of bulging by the intermediate pressing roller. It

The flexible porous sheet may have both end edges of a rectangular expanded shape attached to the cross bar portion, and a part of the cylindrical body may be constituted by the cross bar portion, and both end edges thereof surround the frame body. It may be fixed directly to the frame so that it is mounted in a fixed manner against directional movement, but one or both may be pivotally attached to the frame by suitable pivoting means.

Alternatively, the cylinder may be a cylinder whose entire circumference is constituted by a flexible porous sheet.

A cushion element may be interposed between the outer peripheral surface of the annular portion and both side edge portions of the flexible porous sheet.

The printing drum according to the present invention does not necessarily require a roller as a means for supporting the printing paper from the back side in order to press the printing paper against it, but a flat plate having a highly slippery surface or an arc shape. It may be used together with other printing paper backing means such as a curved plate.

The flexible porous sheet is a single or composite material such as a woven or knitted sheet of fiber or wire, a non-woven sheet of fiber or wire, a sheet of plastic or metal with many small holes, and the like. Which has been prepared so as to have appropriate ink permeability and flexibility.

[0012]

According to the above-mentioned structure, the inner peripheral length of the cylindrical body mainly composed of the flexible porous sheet is required for the inner peripheral length of the cylindrical body to bulge beyond the peripheral length of the outer peripheral surface of the annular portion. By increasing the size by a predetermined dimension, when the pushing force of the centering roller outward in the radial direction is not exerted on any part of the cylindrical body, the clearance between the two due to the difference in diameter between the two is flexible. Due to the elasticity of the sheet, it is in a state in which it is evenly distributed over almost the entire circumference, and when the pushing action in the radial direction by the middle push roller is exerted on any one of the cylindrical bodies, the entire circumference until then. The clearance distributed over the area is quickly concentrated on the portion pushed by the intermediate pushing roller, and the cylindrical body bulges outward in the radial direction more easily at the portion pushed by the intermediate pushing roller.

As an example, when the outer diameter of the annular portion is 150 mm and the outer diameter of the intermediate pressing roller is 50 mm, the inner diameter of the cylindrical body that the cylindrical body should have in advance in order to bulge the cylindrical body by 3 mm. Is 150.40 mm. Therefore, when the clearance between the two is distributed over the entire circumference, the clearance is a very small value of about 0.2 mm.

Thus, according to the above-described structure of the present invention, the degree of printing becomes more uniform in both the longitudinal direction and the width direction of the printed matter, and the deformation of the cylindrical body can be performed easily and quickly. Therefore, the printing speed of the printing apparatus can be further increased.

[0015]

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 attached herewith is a diagram schematically showing the basic construction of a rotary stencil printing machine in which a cylindrical body of a printing drum is constituted mainly by a flexible porous sheet which is the object of the present invention. The basic structure of the rotary stencil printing machine shown in this figure is as described above in Japanese Patent Application No. 63-28553 and Japanese Patent Application No.
It is the same as that disclosed in 47029.
That is, in FIG. 1, 1 is a printing drum, 2 is a back-pressing roller, and 3 is an intermediate-pressing roller. The cylindrical portion of the printing drum 1 excluding both ends is made of a flexible porous sheet,
When the intermediate pressing roller 3 which is rotatably supported by the arm member 5 which pivots about the pivot axis 4 is retracted inside the natural cylindrical shape of the printing drum 1 as shown in FIG. Although the outer peripheral surface of the print drum 1 is separated from the backing roller 2 by a gap 6, as shown in the right side FIG.
When is rotated around the pivot axis 4 in the counterclockwise direction in the figure, the intermediate pressing roller 3 pushes the cylindrical portion of the flexible drum sheet of the printing drum outward in the radial direction, and the pair of feed rollers 7 The printing paper 8 inserted in the gap 6 is pushed between the bulging portion and the back-pressing roller 2, and the stencil is printed around the printing drum 1 by the perforated image of the perforated stencil sheet. Printing is performed on the printing paper 8.

FIG. 2 is a perspective view showing the print drum 1 taken out. The structure of the printing drum shown in FIG. 2 shows the basic configuration proposed in the above-mentioned Japanese Patent Application No. 1-47029, that is, the printing drum has two annular portions 10a constituting both ends thereof. 10b, and a frame member including a cross bar portion 12 connecting these two annular parts, on which a stencil sheet starting end attaching device 14 for selectively attaching the start end of the stencil sheet is provided. There is. In the structure shown, the stencil sheet starting end attachment device 14 has a flap 18 which is rotated by a shaft 16 about an axis of the shaft about 180 degrees, and the starting end of the stencil sheet is crossed. The start end of the stencil sheet is selectively attached to the crossbar portion 12 by selectively sandwiching it between the portion 12 and the flap 18.

A flexible porous sheet 20 having a rectangular expanded shape has annular portions 10 on both side edges 20a and 20b.
It is wound into a cylindrical shape while being freely seated on the outer peripheral surfaces of a and 10b, and constitutes a cylindrical body of the printing drum. Although not shown in this figure, the above-mentioned Japanese Patent Application No. 1-4
In the printing drum proposed in No. 7029, the flexible porous sheet 20 is fixed to the cross bar portion 12 at the starting end portion as viewed along the rotation direction of the printing drum, and the ending end portion. It is attached with a tension load applied by a spring. In the structure of the printing drum shown in FIG. 2, the flexible porous sheet 20 is a net material formed by weaving a wire material.

Gears 22a and 22b are formed integrally with the annular portions 10a and 10b, and these gears are meshed with corresponding gears provided at both ends of the back-pressing roller 2. It engages with a pinion (not shown) incorporated in the printing apparatus, and serves to drive the printing drum to rotate.

FIG. 3 is a similar perspective view showing a print drum having substantially the same construction as the print drum shown in FIG. 2, in which the flexible perforated sheet 20 is shown. It is made of a thin metal plate having elasticity, and has a porous structure by perforating a large number of pores in the central portion except both side edges of the annular portions 10a, 10b which are seated on the outer peripheral surfaces of the annular portions 10a, 10b. . In FIG. 3, parts corresponding to the parts in FIG. 2 are designated by the same reference numerals as in FIG.

One embodiment in which the present invention is incorporated in a printing drum having such a basic structure is shown in FIG. 4 for the sake of clarity of the explanation.

In the illustrated embodiment, the flexible perforated sheet 20 is fixed directly to the crosspiece 12 at its edges 24, 26 adjacent to the crosspiece 12, respectively. The inner peripheral length of the cylindrical body constituted by 20 as a main part (however, in this case, a part of the cylindrical body is given by the cross-section 12) is bulged from the peripheral length of the outer peripheral surfaces of the annular portions 10a, 10b. It is enlarged in advance by the required predetermined size. In the state shown in FIG. 4A on the left side of FIG. 4, the clearance 28 between the two is distributed over the entire circumference based on the circumferential length difference between the two. The clearance 28
Is exaggerated in the drawings for the sake of clarity, but the actual size thereof is as described above.
The outer diameters of a and 10b are 150 mm, and the intermediate pressing roller 3
When the outer diameter is 50 mm, it is a very small value of about 0.2 mm even when a bulge amount of 3 mm is obtained.

FIG. 4B on the right side of FIG. 4 shows that the intermediate pressing roller 3 is biased outward in the radial direction, so that the flexible porous sheet 2 is formed.
The cylindrical body whose main part is 0 is deformed so that a part thereof bulges outward in the radial direction. In this case, the deformation allowance for the flexible porous sheet 20 to bulge at the portion pressed by the intermediate pressing roller 3 can be easily obtained by eliminating the surrounding clearance 28. Moreover, in this case, when forming the cylindrical body having the flexible porous sheet 20 as a main part, both side edge portions thereof are freely seated on the outer peripheral surfaces of the annular portions 10a and 10b. Deformation of the flexible porous sheet from the state shown in FIG. 3 to the state shown in FIG. 3B occurs lightly and quickly, and the relative position of the intermediate pressing roller to the flexible porous sheet moves in the circumferential direction as the printing drum rotates. However, the bulging deformation of the flexible porous sheet follows the transition of the relative position of the intermediate pressing roller with respect to the flexible porous sheet lightly and quickly.

FIG. 5 is a view similar to FIG. 4, showing another embodiment of the present invention modified from the embodiment shown in FIG. 5, parts corresponding to the respective parts shown in FIG.
Are designated by the same reference numerals as in. In the embodiment shown in FIG. 5, a clearance 28 is formed between the outer peripheral surfaces of the annular portions 10a and 10b and both side edges of the flexible porous sheet 20.
A cushion element 30 made of a sheet material having a large elastic deformation rate, such as an elastic foamed resin, is interposed in the portion. By providing such a cushion element 30, as shown in FIG. A on the left side, when the intermediate pressing roller 3 is in the retracted position, the cylindrical body having the flexible porous sheet 20 as a main portion and the annular portion 10 are provided.
The clearance 28 left between a and 10b remains more uniform over the entire circumference of the print drum. Also, the cushion element 30, when made of a suitable material, can exert the effect of preventing the ink inside the printing drum from leaking out. In order to perform such a function, the cushion element 30 may have a sponge-like structure having a bubble structure, in which case the bubble has a closed closed-cell structure that gives elasticity but does not contain ink as much as possible. Preferably. Cushion element 3
0 may be fixed to either the flexible porous sheet 20 or the annular portions 10a and 10b with an adhesive or the like.

Even when such a cushion element 30 is provided, since the cushion element is made of a material having a high elastic deformation rate, the thickness thereof can be easily reduced by compression. Therefore, as shown in FIG. When a part of the cylindrical body formed by the flexible porous sheet is bulged outward in the radial direction, the cushion element easily reduces its thickness at a necessary position, and the flexible porous sheet is shown in FIG. In the embodiment, it can be deformed into substantially the same shape.

FIGS. 6 and 7 are similar views showing one modification of the embodiment shown in FIGS. 4 and 5, respectively. In these modifications, both ends 24, 26 of the flexible perforated sheet 20 are attached to the crosspiece 1 via pivoting means 32, 34.
It is attached to 2. Thus, when both edges (or one edge) of the flexible perforated sheet are attached to the frame through the pivoting means, the clearance 28 is less than 0.
Although it is a very small value of about 2 mm, the softness when the flexible porous sheet bulges out at a position very close to the cross section 12 is further increased. The other structure and operation of the modification shown in FIGS. 6 and 7 are the same as those in the embodiment shown in FIGS. 4 and 5.

As can be understood from the above description, in the printing drum shown in FIGS. 4 to 7, the rectangular flexible porous sheet 20 forming the flexible cylindrical surface of the printing drum has the front end 24 thereof. And at the rear end 26 it is fixedly attached to the crosspiece 12 either directly or by means of pivoting means 32, 34 with respect to the circumference, and a rectangular flexible perforated sheet of cylindrical body with the crosspiece is formed. The circumference is constant, and when a part of the circumference is not swollen by the intermediate pressing roller, the circumference is in close contact with the annular portions 10a and 10b with a minute clearance of about 0.2 mm, and thus the flexibility is high. There is no risk of ink leakage between the side edges and the annular portion of the porous sheet,
Moreover, when the pushing action by the intermediate pressing roller is exerted during printing, the required local bulge of about 3 mm can be easily generated immediately. As described above, when the flexible porous sheet is fixedly attached to the cross section at both ends thereof with respect to the circumferential length, the above-mentioned Japanese Patent Application No. 1-47.
In the case where the rear end of the flexible porous sheet is pulled to the cross bar by a spring as in the printing drum proposed in No. 029, the stencil sheet is peeled from the printing drum and is flexible during plate ejection. The porous porous sheet is prevented from being lifted from the cylindrical portion by being dragged by the base paper to be discharged due to the viscosity of the ink, and the cylindrical body of the flexible porous sheet is maintained in a stable state even during the plate discharging.

4 to 7, in order to functionally explain the constitution of the present invention and to clarify the display of the drawings, the flexible porous sheet is directly attached to the cross-sections at the front and rear ends thereof. The attachment of the flexible perforated sheet is shown by a single line, either directly on the cross section or directly by means of a ring. Although it is shown in the structure that it is simply joined via the pivotal attachment means, at this joint, any attachment using a mounting screw, a latch, etc. for convenient attachment and replacement of the flexible porous sheet is performed. Obviously the structure may be incorporated.

8 and 9 are schematic views corresponding to A of FIG. 4 and A of FIG. 5 showing still another embodiment of the present invention. In these embodiments, the cylindrical body having the flexible perforated sheet 20 as a main part constitutes the entire circumference of the cylindrical body by itself, that is, without forming the cross section 12 as a part of the structure. ing. The radial position of the cylindrical body at the portion where the cylindrical body overlaps with the crosspiece portion may coincide with the outer peripheral surfaces of the annular portions 10a and 10b, or the annular portion of the annular portion may be completely concentric with the annular portion. It may be separated from the outer peripheral surface, but in any case, the difference is 0.
It is about 2 mm. 8 and 9 show an embodiment in which the cylindrical body is attached to the crosspiece portion 12 so as to be completely concentric with the annular portion, but the annular clearance in the drawings is, of course, for the purpose of clarifying the illustration. Shown exaggerated.

In the above, the present invention has been described in detail with reference to some preferred embodiments, but the present invention is not limited to these embodiments, and various other implementations are possible within the scope of the present invention. It will be apparent to those skilled in the art that examples are possible.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the basic configuration of a rotary stencil printing machine using a printing drum made of a flexible cylinder.

FIG. 2 is a perspective view showing an example of a printing drum in the case where a flexible porous sheet forming a flexible cylinder is a net material formed by weaving a wire material.

FIG. 3 is a perspective view showing an example of a printing drum in the case where a flexible porous sheet forming a flexible cylinder is made of a sheet material in which holes are perforated in a metal plate.

FIG. 4 is a schematic diagram showing one embodiment of a printing drum according to the present invention in two operating states in connection with a middle press roller.

FIG. 5 is a schematic diagram showing another embodiment of a printing drum according to the present invention in two operating states in connection with a middle press roller.

6 is a view similar to FIG. 4 showing a modification of the embodiment shown in FIG. 4;

7 is a view similar to FIG. 5 showing a modification of the embodiment shown in FIG.

FIG. 8 is a schematic view similar to FIG. 4A showing yet another embodiment of the printing drum according to the present invention.

9 is a schematic view similar to FIG. 5A showing yet another embodiment of a printing drum according to the present invention.

[Explanation of symbols]

 1 ... Printing drum 2 ... Back pressing roller 3 ... Middle pressing roller 4 ... Pivot axis 5 ... Arm member 6 ... Gap 7 ... Printing paper feed roller 8 ... Printing paper 10a, 10b ... Annular part 12 ... Cross bar part 14 ... Device 16 ... Shaft 18 ... Flap 20 ... Flexible porous sheet 20a, 20b ... Both side edges 22a, 22b ... Gear 24, 26 ... Edge of flexible porous sheet 28 ... Clearance 30 ... Cushion Elements 32, 34 ... Pivoting means

Claims (5)

[Claims] 1. A printing drum comprising a cylindrical body having a porous structure for carrying a perforated stencil sheet in a wound state, and ink supplied from the inside of the cylindrical body extends along the inner surface of the cylindrical body. The stencil is pushed by the rolling middle push roller and is supplied to the stencil sheet through the hole of the cylinder body, and a part of the cylinder body is bulged outward in the radial direction by a predetermined substantial bulge by the middle push roller. A printing drum of a rotary type stencil printing apparatus which performs stencil printing on a printing paper pressed against the cylindrical body by a back-pressing means while the printing drum rotates while constituting both ends of the printing drum. A frame body including two annular portions and a cross-bar portion that connects the two annular portions and selectively attaches the starting end of the stencil sheet, and a frame member including a stencil sheet starting end attaching device, and the two annular portions at both side edges. Free on each outer surface A printing drum including a flexible porous sheet having a substantially rectangular expanded shape capable of being seated and forming a main part of the cylindrical body, and the inner peripheral length of the cylindrical body is equal to that of the outer peripheral surface of the annular portion. A printing drum, which is preliminarily made larger than a circumference by a predetermined dimension that allows the predetermined amount of swelling by the intermediate pressing roller. 2. The printing drum according to claim 1, wherein the flexible porous sheet has both end edges of a rectangular expanded shape attached to the cross bar portion, and a part of the cylindrical body is constituted by the cross bar portion. A printing drum characterized by that. 3. The printing drum according to claim 2, wherein the flexible porous sheet is pivotally attached to the cross section at at least one of both end edges of a rectangular expanded shape. 4. The printing drum according to claim 1, wherein the cylinder is a cylinder whose entire circumference is constituted by a flexible porous sheet. 5. A printing drum according to any one of claims 1 to 4, wherein cushion elements are interposed between both side edge portions of the flexible porous sheet and the outer peripheral surface of the annular portion. And a printing drum.